Microwave dielectric properties of AWO4 (A = Ca, Ba, Sr) ceramics synthesized via high energy ball milling method

Abstract The AWO 4 (A = Ca, Sr, Ba) compounds with scheelite structure were synthesized by high energy ball milling for 30 min and the average particle size was reduced to about 120 nm after milling 30 h. AWO 4 ceramics were well sintered at relatively low temperatures of 900–1000 °C, 200–400 °C lower than those required by a conventional solid state reaction technique. The samples of CaWO 4 , SrWO 4 , and BaWO 4 ceramics have dense microstructures and excellent microwave dielectric properties, ɛ r  = 10.7, 8.6, 8.4; Q  ×  f  = 62,100 GHz, 57,500 GHz, 58,800 GHz; and τ f  = −48 ppm/°C, −52 ppm/°C, −64 ppm/°C, respectively.